Firstly, I did not say that B12 or lack of can cause constipation because it does not. What I said is lack of choline can promote constipation due to lack of acetylcholine which is a stimulator to the bowel. Therefore taking some lecithin such as sunflower lecithin might be helpful. Any would be helpful.
Lyme is a problem and I did just read about some essential oils which can be helpful because I was reading about mycoplasma infections. I am trying to cover so many bases for all the infections in my stomach. There are so many possible causes. It does not help that the researcher use different units so comparing one thing with another and trying to find the strongest is very difficult. Some use uL/mL whereas others use ug/mL or mg/mL and some use ppm. Comparing these is extremely difficult.
Re: sinuses. High histamine levels does provoke sinusitis because of common infections in the nose. Lowering histamine would be helpful while you deal with the other issues and could make things easier ie breathing. I have had in the past a similar situation with breathing myself where I could not breath through my nose at various times not caused by any obvious infection. It does prevent proper breathing and forces a person to breath backwards. Not deeply through the nose, expanding the lower stomach and then out through the mouth which helps relax the body.
Look up anti histamines and/or natural anti histamines. I seem to remember that Quercetin can be helpful in this regard but I seem to remember there being some bioavailability issues. Chinese Skullcap can also be helpful. It does also have certain efflux pump inhibiting properties which I intend to make use of because I do have an extract of this myself from a Chinese herbalist as 100g powder it's called Huang Qin (Scutellaria Baicalensis). It is also believed to cause damage to bacterial cell membranes which might also be a helpful property.
High dose Magnesium might also be helpful, well above 800mg/day. It is an essential mineral. Some will be used by biofilms to help hold them together.
Lowering cortisol levels would be helpful because cortisol increases many of the effects that you are experiencing ie coldness, mucus production so lowering it would be very helpful IMO. You probably have weak kidney energy which causes high background cortisol levels. This all shows in the irises. It does also affect the mood.
I use Tu Si Zi (dodder seed) to do this. It tones the liver and kidney energies and lowers cortisol levels. It does also increase the weight of the pituitary gland and improves it's function in tests done on animals. When I do not take it my hands and feet feel very cold. It is often taken with Gou Qi Zi (wolfbery/goji berry) which complement each other. That berry can stimulate the immune system which could have both positive and negative results. Positive against bacteria such as lyme but negative against autoimmunity. I would try Tu Si Zi as a minimum because it should be helpful. I use 15 grams/day boiled in water for 1 hour, it is meant to be 30 minutes but I prefer to maximize extraction. Larger quantities can be boiled in one go in a large saucepan. Just use around 15g/day whatever the fraction of the liquid. It needs to be strained and watch for a slight blue oil on top of the brown water when seen with a decent light source sunlight preferable, it is an essential oil which does the kidney/Liver toning.
Your body will have very high demands on nutrients because of high detox demands. Do not underestimate methylation nutrients because it affects so many processes in the human body. Ensure you are getting sufficient of the methylation nutrients.
Siberian Ginseng would also be worth considering to lower cortisol.